Thermosetting Resin Composition for Producing Color Filter for CMOS Image Sensor, Color Filter Comprising Transparent Film Formed Using the Composition and CMOS Image Sensor Using the Color Filter

ABSTRACT

A thermosetting resin composition for producing a color filter for a CMOS image sensor is provided. The thermosetting resin composition comprises an organic solvent and a self-curing copolymer having structural units represented by Formulae 1, 2, 3 and 4, which are described in the specification.

CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional application is a divisional of U.S. applicationSer. No. 12/116,314, filed May 7, 2008, which is itself acontinuation-in-part of U.S. application Ser. No. 11/965,856, filed Dec.28, 2007, each of which is hereby incorporated by reference in theirentirety, and claims priority therefrom under 35 USC Section 120. Thisapplication also claims priority under 35 USC Section 119 from KoreanPatent Application No. 10-2007-0059842, filed on Jun. 19, 2007, which isalso hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a thermosetting resin composition forproducing a color filter for a CMOS image sensor, a color filtercomprising a transparent film formed using the composition, and a CMOSimage sensor using the color filter.

BACKGROUND OF THE INVENTION

Color filters used in an image sensor can include a transparent filmformed under or on the surface of the color filter to improve flatnessand to protect the color filter. The transparent film must be opticallytransparent in the visible region, have high film strength and exhibitsufficient heat and chemical resistance to withstand subsequentprocesses such as heating, cleaning, development and etching afterforming the transparent film. In particular, an underlying transparentfilm of a color filter for an image sensor should be capable ofsuppressing the reflection of UV rays which are irradiated to pattern acolor resist, to thereby prevent the occurrence of pattern defects inthe color filter by various adverse factors such as halation andstanding waves.

Japanese Patent Publications Nos. Hei 1-134306, Sho 62-163016 and Sho63-131103 disclose compositions for transparent films for color filterscomprising glycidyl methacrylate, polyimide and a mixture of a melamineresin and an epoxy resin as the primary components, respectively.

Epoxy resin compositions can be used to produce protective films forcolor filters having reliable adhesive strength, heat resistance,chemical resistance and water resistance. For instance, Japanese PatentPublication No. Hei 08-050289 teaches a curable resin compositioncomprising a glycidyl methacrylate polymer and a phenolic curing agent.Further, Japanese Patent Publication No. Hei 08-201617 teaches a resincomposition for a transparent film comprising an epoxy resin, a curingagent and an organic solvent wherein the curing agent is a reactionproduct of a styrene-maleic anhydride copolymer and an amine.

Generally epoxy resins are mixed with curing agents (so-called “two-partcompositions”) immediately before use due to their rapid reaction withthe curing agents. It is known that epoxy resins are unsuitable for usein the preparation of one-part compositions. Two-part compositions,however, are complicated to handle and unsuitable for industrial-scalepreparation.

None of the aforementioned prior art techniques discloses one-partcompositions comprising an epoxy resin while simultaneously satisfyingthe requirements for transparency, film strength, heat resistance, acidresistance and alkali resistance. Further, a transparent film for acolor filter capable of absorbing UV light has not yet been developed.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there isprovided a thermosetting resin composition for producing a color filter.The thermosetting resin composition of the invention can exhibitexcellent adhesive strength, transparency, film strength, heatresistance, acid resistance, alkali resistance and long-term storagestability and can absorb UV light of a particular wavelength.

The thermosetting resin composition of the invention comprises anorganic solvent and a self-curing copolymer having structural unitsrepresented by Formulae 1, 2, 3 and 4:

-   -   wherein R₁ is a hydrogen atom or a methyl group and n is an        integer from 1 to 10;

-   -   wherein R₂ is a hydrogen atom or a methyl group and m is an        integer from 1 to 10;

-   -   wherein R₃ is a hydrogen atom or a methyl group; and

-   -   wherein R₄ is a hydrogen atom or a methyl group and Z is        selected from the following groups:

The self-curing copolymer can include about 5 to about 90 mol % of thestructural unit of Formula 1, about 1 to about 30 mol % of thestructural unit of Formula 2, about 1 to about 30 mol % of thestructural unit of Formula 3, and about 0.5 to about 20 mol % of thestructural unit of Formula 4.

The self-curing copolymer may further include a structural unit ofFormula 6:

wherein X is selected from

o is an integer from 1 to 4, p is an integer from 4 to 12, and Y isselected from a hydrogen atom, C₁-C₄ lower alkyl groups and C₁-C₄ loweralkoxy groups.

The structural unit of Formula 6 can be present in an amount of about0.5 to about 20 mol %.

The self-curing copolymer can have a weight-average molecular weightranging from about 1,000 to about 1,000,000.

The thermosetting resin composition of the present invention may furthercomprise an epoxy compound.

The thermosetting resin composition of the present invention maycomprise about 1 to about 45% by weight of the self-curing copolymer,about 1 to about 45% by weight of the epoxy compound, and the balance ofthe organic solvent.

The epoxy compound can be selected from the group consisting ofbisphenol A type epoxy, bisphenol F type epoxy, phenol novolak typeepoxy, cresol novolak type epoxy and substituted epoxy compounds. Theseepoxy compounds may be used alone or as a mixture thereof.

The self-curing copolymer can further include at least one structuralunit selected from the group consisting of: (meth)acrylates includingmethyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate,isopropyl (meth)acrylate, butyl (meth)acrylate, and benzyl(meth)acrylate; acrylamides including N-methylacrylamide,N-ethylacrylamide, N-isopropylacrylamide, N-methylolacrylamide,N-methylmethacrylamide, N-ethylmethacrylamide,N-isopropylmethacrylamide, N-methylolmethacrylamide,N,N-dimethylacrylamide, N,N-diethylacrylamide,N,N-dimethylmethacrylamide, and N,N-diethylmethacrylamide; styrenesincluding styrene, α-methylstyrene, and hydroxystyrene;N-vinylpyrrolidone; N-vinylformamide; N-vinylamide; andN-vinylimidazole.

The composition of the present invention may further comprise at leastone polymer selected from poly(meth)acrylate, nylon, polyester,polyimide and polysilicon. The polymer can be present in an amount ofabout 50 parts by weight or less, based on 100 parts by weight of theself-curing copolymer.

In accordance with another aspect of the present invention, there isprovided a color filter comprising a transparent film formed using thecomposition.

In accordance with still another aspect of the present invention, thereis provided an image sensor using the color filter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating the structure of a CMOS imagesensor.

FIG. 2 is a schematic diagram illustrating a mechanism for an occurrenceof pattern defects by light reflection.

FIG. 3 shows shapes of a pattern obtained by applying a color resist fora CMOS image sensor to a transparent film formed in Comparative Example1, exposing the color resist to light and developing the exposed colorresist.

FIG. 4 shows shapes of a pattern obtained by applying a color resist fora CMOS image sensor to a transparent film formed in Example 1, exposingthe color resist to light and developing the exposed color resist.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter inthe following detailed description of the invention, in which some, butnot all embodiments of the invention are described. Indeed, thisinvention may be embodied in many different forms and should not beconstrued as limited to the embodiments set forth herein; rather, theseembodiments are provided so that this disclosure will satisfy applicablelegal requirements.

The present invention provides a thermosetting resin composition, whichcan be used to produce a color filter for a CMOS image sensor.Specifically, the thermosetting resin composition of the presentinvention comprises an organic solvent and a self-curing copolymerhaving ultraviolet light (UV) absorbing groups.

The self-curing copolymer has structural units represented by Formulae1, 2, 3 and 4:

-   -   wherein R₁ is a hydrogen atom or a methyl group and n is an        integer from 1 to 10;

-   -   wherein R₂ is a hydrogen atom or a methyl group and m is an        integer from 1 to 10;

-   -   wherein R₃ is a hydrogen atom or a methyl group; and

-   -   wherein R₄ is a hydrogen atom or a methyl group and Z is        selected from the following groups:

The self-curing copolymer has thermosetting properties because thestructural unit of Formula 1 is thermally crosslinked with thestructural units of Formulae 2, 3 and 4. The self-curing copolymerhaving the structural units of Formulae 1 to 4 may be of any type suchas a random, alternating, block or graft copolymer.

The self-curing copolymer can include about 5 to about 90 mol % of thestructural unit of Formula 1, about 1 to about 30 mol % of thestructural unit of Formula 2, about 1 to about 30 mol % of thestructural unit of Formula 3, and about 0.5 to about 20 mol % of thestructural unit of Formula 4.

In particular, the structural unit of Formula 4 has a UV-absorbing group(Z). The presence of the group (Z) prevents the occurrence of patterndefects resulting from various adverse factors. As an example, referringto the mechanism illustrated in FIG. 2, when a color resist is exposedto light, unexposed portions of the color resist are not cured byre-reflection of UV light from an underlying substrate.

The self-curing copolymer may optionally further comprise a structuralunit of Formula 6, the presence of which can improve the storagestability and film hardness of the composition:

wherein X is selected from

o is an integer from 1 to 4, p is an integer from 4 to 12, and Y isselected from a hydrogen atom, C₁-C₄ lower alkyl groups and C₁-C₄ loweralkoxy groups.

The structural unit of Formula 6 can be present in an amount of about0.5 to about 20 mol %.

The weight-average molecular weight of the self-curing copolymer can bebetween about 1,000 and about 1,000,000. When the self-curing copolymerhas a weight-average molecular weight less than about 1,000, theself-curing copolymer may not be sufficiently curable. Meanwhile, whenthe self-curing copolymer has a weight-average molecular weight greaterthan about 1,000,000, the copolymer may have reduced solubility or itmay be difficult to apply the composition to a substrate. Theself-curing copolymer can be present in the thermosetting resincomposition in an amount of about 1 to about 45% by weight, based on thetotal weight of the composition.

The kind of the organic solvent used in the composition of the presentinvention is not particularly restricted. Examples of organic solventsuseful in the invention include without limitation: ethylene glycolsincluding ethylene glycol and diethylene glycol; glycol ethers includingethylene glycol monomethyl ether, diethylene glycol monomethyl ether,ethylene glycol diethyl ether, and diethylene glycol dimethyl ether;glycol ether acetates including ethylene glycol monoethyl ether acetate,diethylene glycol monoethyl ether acetate, and diethylene glycolmonobutyl ether acetate; propylene glycols; propylene glycol ethersincluding propylene glycol monomethyl ether, propylene glycol monoethylether, propylene glycol monopropyl ether, propylene monobutyl ether,propylene glycol dimethyl ether, dipropylene glycol dimethyl ether,propylene glycol diethyl ether, and dipropylene glycol diethyl ether;propylene glycol ether acetates including propylene glycol monomethylether acetate and dipropylene glycol monoethyl ether acetate; amidesincluding N-methylpyrrolidone, dimethylformamide, and dimethylacetamide;ketones including methyl ethyl ketone (MEK), methyl isobutyl ketone(MIBK), and cyclohexanone; petroleum solvents including toluene, xylene,and solvent naphtha; esters including ethyl acetate, butyl acetate, andethyl lactate; and mixtures thereof.

The organic solvent makes up the remaining weight percent of thecomposition in addition to the contents of the self-curing copolymer andother components. The composition of the present invention may comprisethe organic solvent in an amount of about 30 to about 99% by weight, forexample about 70 to about 98% by weight, based on the total weight ofthe composition. If the composition includes less than about 30% byweight of the organic solvent, it can be difficult to apply thecomposition to a substrate. Meanwhile, if the composition includes morethan about 99% by weight of the organic solvent, it can be difficult toform a sufficiently thick protective film.

For improvements in etching resistance and alkali resistance and theadjustment of fluidity, the composition may optionally further comprisean epoxy compound. The epoxy compound can be an epoxy compound selectedfrom the group consisting of bisphenol A type epoxy, bisphenol F typeepoxy, phenol novolak type epoxy, cresol novolak type epoxy andsubstituted epoxy compounds, and the like. These epoxy compounds may beused alone or as a mixture thereof. The epoxy compound can have aweight-average molecular weight ranging from about 50 to about 10,000.The content of the epoxy compound in the thermosetting resin compositioncan be in the range of about 1 to about 45% by weight, for example about5 to about 30% by weight, based on the total weight of the resincomposition. The presence of the epoxy compound in an amount of lessthan about 1% by weight can result in a degradation in the dimensionstability of a transparent film formed using the composition. Meanwhile,the presence of the epoxy compound in an amount greater than about 45%by weight may make it difficult to apply the composition to a substrate.

To improve or impart other properties to the composition such as ease ofapplication, film hardness and affinity for overlying and underlyingfilms, the self-curing copolymer may optionally further include at leastone repeating unit selected from the group consisting of:(meth)acrylates including methyl (meth)acrylate, ethyl (meth)acrylate,propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate,and benzyl (meth)acrylate; acrylamides including N-methylacrylamide,N-ethylacrylamide, N-isopropylacrylamide, N-methylolacrylamide,N-methylmethacrylamide, N-ethylmethacrylamide,N-isopropylmethacrylamide, N-methylolmethacrylamide,N,N-dimethylacrylamide, N,N-diethylacrylamide,N,N-dimethylmethacrylamide, and N,N-diethylmethacrylamide; styrenesincluding styrene, α-methylstyrene, and hydroxystyrene;N-vinylpyrrolidone; N-vinylformamide; N-vinylamide; andN-vinylimidazole; and the like, and mixtures thereof.

The self-curing copolymer can be synthesized using any suitable processknown in the art. As a non-limiting example, the self-curing copolymercan be synthesized using a radical polymerization initiator in the sameorganic solvent as the thermosetting resin composition of the presentinvention.

The organic solvent used for the synthesis of the self-curing copolymerhaving UV-absorbing groups is not particularly restricted and can be thesame as that of the thermosetting resin composition of the presentinvention. On the other hand, the amount of the organic solvent used inthe polymerization can be controlled such that the self-curing copolymeris present in an amount of about 3 to about 50% by weight, for exampleabout 5 to about 30% by weight, based on the weight of the solution ofthe self-curing copolymer in the organic solvent. When the concentrationof the self-curing copolymer in the solution is less than about 3% byweight, the polymerization rate may be low and thus some of the monomersmay remain unreacted. Meanwhile, when the concentration of theself-curing copolymer in the solution exceeds about 50% by weight, thesolution can be too viscous to handle and to control the reaction rate.

Any known polymerization initiator can be used for the synthesis of theself-curing copolymer, including thermal polymerization initiators,photopolymerization initiators, and redox initiators. Peroxide type andazo type radical polymerization initiators can be useful in theinvention because of ease of handling and controlling reaction rate andmolecular weight.

Examples of peroxide type polymerization initiators that can be used inthe present invention include methyl ethyl ketone peroxide,cyclohexanone peroxide, methyl cyclohexanone peroxide, acetyl acetoneperoxide, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane,1,1-bis(tert-butylperoxy)cyclohexane,1,1-bis(tert-hexylperoxy)-3,3,5-trimethylcyclohexane,1,1-bis(tert-hexylperoxy)cyclohexane,1,1-bis(tert-butylperoxy)cyclododecane, isobutyl peroxide, lauroylperoxide, succinic acid peroxide, 3,5,5-trimethylhexanoyl peroxide,benzoyl peroxide, octanoyl peroxide, stearoyl peroxide, diisopropylperoxydicarbonate, di-n-propyl peroxydicarbonate, di-2-ethylhexylperoxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di-2-methoxybutylperoxydicarbonate, bis-(4-tert-butylcyclohexyl) peroxydicarbonate,(α,α-bis-neodecanoylperoxy)diisopropylbenzene, cumyl peroxyneodecanoate,octyl peroxyneodecanoate, hexyl peroxyneodecanoate, tert-butylperoxyneodecanoate, tert-hexyl peroxypivalate, tert-butylperoxypivalate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane,1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate,peroxy-2-ethyl-tert-hexyl hexanoate, peroxy-2-ethyl-tert-butylhexanoate, peroxy-2-ethyl-tert-butyl hexanoate,peroxy-3-methyl-tert-butyl propionate, tert-butyl peroxylaurate,tert-butylperoxy-3,5,5-trimethylhexanoate, tert-hexyl peroxyisopropylmonocarbonate, tert-butylperoxy isopropyl carbonate,2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, tert-butyl peracetate,tert-hexyl perbenzoate, tert-butyl perbenzoate, and the like andmixtures thereof. Combinations of the peroxide type polymerizationinitiators with reductants can be used as redox initiators.

Examples of azo type polymerization initiators that can be used in thepresent invention include 1,1-azobis(cyclohexane-1-carbonitrile),2,2′-azobis(2-methyl-butyronitrile), 2,2′-azobisbutyronitrile,2,2′-azobis(2,4-dimethyl-valeronitrile),2,2′-azobis(2,4-dimethyl-4-methoxyvaleronitrile),2,2′-azobis(2-amidino-propane) hydrochloride,2,2′-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]hydrochloride,2,2′-azobis[2-(2-imidazolin-2-yl)propane]hydrochloride,2,2′-azobis[2-(5-methyl-2-imidazolin-2-yl)propane],2,2′-azobis[2-methyl-N-(1,1-bis(2-hydroxymethyl)-2-hydroxyethyl]propionamide,2,2′-azobis[2-2-methyl-N-(2-hydroxyethyl)propionamide],2,2′-azobis(2-methyl-propionamide) dihydrate, 4,4′-azobis(4-cyano-valeicacid), 2,2′-azobis(2-hydroxymethylpropionitrile),2,2′-azobis(2-methylpropionic acid)dimethyl ester(dimethyl-2,2′-azobis(2-methylpropionate)), cyano-2-propylazoformamide,and the like, and mixtures thereof.

In addition to these peroxide and azo type polymerization initiators, atleast one known molecular weight-controlling agent such as achain-transfer agent, a chain-terminating agent or a polymerizationpromoter can be further added during synthesis of the self-curingcopolymer to adjust the molecular weight of the self-curing copolymer toa range such as defined above. Suitable molecular weight-controllingagents can be mercaptopropionic acid, mercaptopropionate, thioglycol,thioglycerin, dodecylmercaptan, α-methylstyrene dimers, and the like,and mixtures thereof.

One or more solvents other than the organic solvent used for thepreparation of the copolymer can be added for the purpose of assistingthe solubility of the constituent component(s) and controlling theleveling properties and drying rate after the polymerization.

In addition, the copolymer can be extracted into a solid form for thepurpose of purification, storage and solvent change by known techniques,without limitation, such as spray drying, film drying, dropping intopoor solvents and re-dipping.

In order to improve etching resistance and alkali resistance and adjustfluidity, the composition of the present invention can further compriseat least one polymer of poly(meth)acrylate, nylon, polyester, polyimide,or polysilicon in an amount of about 50 parts by weight or less, basedon 100 parts by weight of the self-curing copolymer.

A thermosetting catalyst can be further added to the thermosetting resincomposition of the present invention. Exemplary thermosetting catalystsuseful in the invention include amine compounds, phosphorus compounds,boron compounds, antimony compounds, carboxylic acid compounds, organicsulfonic acid compounds, and the like, and mixtures thereof. For goodstorage stability, the thermosetting catalyst can be added in an amountof about 10 parts by weight or less, based on 100 parts by weight of theself-curing polymer.

If required, the thermosetting resin composition of the presentinvention may be further blended with other known agents, e.g.,antioxidants, UV stabilizers, plasticizers, leveling agents, fillers,and the like, and mixtures thereof.

The thermosetting resin composition of the present invention can beapplied to a substrate using known techniques, e.g., screen printing,curtain coating, blade coating, spin coating, spray coating, dipcoating, flow coating, roll coating or slit coating, to form a film. Thefilm thus formed can have a thickness ranging from about 0.1 to about3.0 μm, for example, about 0.2 to about 1.5 μm, after subsequent drying.If the film is thinner than about 0.1 μm, sufficient flatness relativeto step height cannot be attained. Meanwhile, if the film is thickerthan about 3.0 μm, the transmittance is lowered, considerable drying andcuring time are required and the productivity is reduced.

The substrate coated with the thermosetting resin composition of thepresent invention can be dried and heat-cured to evaporate the solvent,and cured by crosslinking to form a sufficiently hard film. The dryingand the heat-curing processes can be carried out simultaneously orseparately. It can be advantageous to carry out the drying andheat-curing processes separately because rapid heating may lead toformation of foams and cracks in the film.

Exemplary apparatus for the drying process include, without limitation,hot-air dryers, far-infrared dryers and hot plates. The drying processcan be conducted at a temperature ranging from about 50° C. to about150° C. The drying time can vary, depending on the capacity of the dryerused, air flow, temperature and film thickness. An exemplary drying timeis between about 1 and about 10 minutes.

Exemplary apparatus for the heat-curing process include withoutlimitation, hot-air ovens, far-infrared ovens and hot plates. Theheat-curing process can be conducted at a temperature ranging from about150° C. to about 250° C. Curing may not be satisfactory below about 150°C. Meanwhile, depolymerization and carbonization of the polymers mayoccur above about 250° C. and deteriorate performance of the final film.

The film formed with the thermosetting resin composition of the presentinvention can be applied to a color filter for an image sensor.

Hereinafter, the present invention will be explained in more detail withreference to the following examples and comparative examples. However,these examples are given for the purpose of illustration and are notintended to limit the invention.

EXAMPLES Example 1

After 600 g of propylene glycol monomethyl ether acetate is put into a1,000 ml flask equipped with a reflux condenser and an agitator, thetemperature is raised to 80° C. with stirring. A mixture of 25 g ofglycidyl methacrylate, 13 g of 2-hydroxyethyl methacrylate, 15 g ofmethacrylic acid, 9 g of 9-anthracenemethyl methacrylate, 4 g ofN-phenylmaleimide, 9 g of styrene, 100 g of methyl methacrylate and 20 gof dimethyl-2,2′-azobis(2-methylpropionate) is added dropwise to theflask for 1.5-2 hours while maintaining the temperature at 80° C. withstirring. The resulting mixture is allowed to react for 3-4 hours withstirring while maintaining the reaction temperature at 80° C. to obtaina solution (a) containing the random copolymer of Formula 7.

Gel permeation chromatography (GPC) of the polymer solution indicates aweight-average molecular weight of 14,500, as measured on a polystyrenebasis.

To 20 g of the polymer solution (a) are added 1 g of an epoxy resin(jER-152, JER), 0.05 g of a surfactant (R-08, DIC) and 50 g of propyleneglycol monomethyl ether acetate. The mixture is dissolved withsufficient stirring and filtered to obtain a thermosetting resincomposition (e).

The thermosetting resin composition (e) is applied to a 0.7 mm thickglass substrate (#1737, Corning) using a spin coater, dried in a dryerat 80° C. for 3 minutes, and cured at 230° C. for 30 minutes to producea 0.5 μm thick transparent film.

Example 2

After 600 g of propylene glycol monomethyl ether acetate is put into a1,000 ml flask equipped with a reflux condenser and an agitator, thetemperature is raised to 80° C. with stirring. A mixture of 30 g ofglycidyl methacrylate, 10 g of 2-hydroxyethyl methacrylate, 15 g ofmethacrylic acid, 5 g of 2-hydroxy-4-methacryloyloxybenzophenone, 5 g ofN-phenylmaleimide, 10 g of styrene, 50 g of methyl methacrylate and 8 gof dimethyl-2,2′-azobis(2-methylpropionate) is added dropwise to theflask for 1.5-2 hours while maintaining the temperature at 80° C. withstirring. The resulting mixture is allowed to react for 4-5 hours withstirring while maintaining the reaction temperature at 80° C. to obtaina solution (b) containing the random copolymer of Formula 8.

Gel permeation chromatography (GPC) of the polymer solution indicates aweight-average molecular weight of 11,000, as measured on a polystyrenebasis.

A thermosetting resin composition (f) is prepared in the same manner asin Example 1, except that 40 g of the polymer solution (b) is usedinstead of the polymer solution (a).

A 0.5 μm thick transparent film is produced in accordance with theprocedure described in Example 1, except that the thermosetting resincomposition (f) is used instead of the thermosetting resin composition(e).

Example 3

After 600 g of propylene glycol monomethyl ether acetate is put into a1,000 ml flask equipped with a reflux condenser and an agitator, thetemperature is raised to 80° C. with stirring. A mixture of 30 g ofglycidyl methacrylate, 10 g of 2-hydroxyethyl methacrylate, 15 g ofmethacrylic acid, 100 g methyl methacrylate, 10 g of2-(2′-hydroxy-5′-methacryloyloxyphenyl)benzotriazole, 15 g ofN-phenylmaleimide, 33 g of styrene and 8 g ofdimethyl-2,2′-azobis(2-methylpropionate) is added dropwise to the flaskfor 1.5-2 hours while maintaining the temperature at 80° C. withstirring. The resulting mixture is allowed to react for 4-5 hours withstirring while maintaining the reaction temperature at 80° C. to obtaina solution (c) containing the random copolymer of Formula 9.

Gel permeation chromatography (GPC) of the polymer solution indicates aweight-average molecular weight of 9,500, as measured on a polystyrenebasis.

A thermosetting resin composition (g) is prepared in the same manner asin Example 1, except that 40 g of the polymer solution (c) is usedinstead of the polymer solution (a).

A 0.5 μm thick transparent film is produced in accordance with theprocedure described in Example 1, except that the thermosetting resincomposition (g) is used instead of the thermosetting resin composition(e).

Comparative Example 1

After 600 g of propylene glycol monomethyl ether acetate is put into a1,000 ml flask equipped with a reflux condenser and an agitator, thetemperature is raised to 80° C. with stirring. A mixture of 30 g ofglycidyl methacrylate, 13 g of dicyclopentanyl methacrylate, 12 g ofstyrene, 25 g of methyl methacrylate and 10 g ofdimethyl-2,2′-azobis(2-methylpropionate) is added dropwise to the flaskfor 1.5-2 hours while maintaining the temperature at 80° C. withstirring. The resulting mixture is allowed to react for 4-5 hours withstirring while maintaining the reaction temperature at 80° C. to obtaina solution (d) containing the random copolymer of Formula 10.

Gel permeation chromatography (GPC) of the polymer solution indicates aweight-average molecular weight of 13,000, as measured on a polystyrenebasis.

A thermosetting resin composition (h) is prepared in the same manner asin Example 1, except that 40 g of the polymer solution (d) is usedinstead of the polymer solution (a).

A 0.5 μm thick transparent film is produced in accordance with theprocedure described in Example 1, except that the thermosetting resincomposition (h) is used instead of the thermosetting resin composition(e).

Evaluation of Physical Properties

The transparent films produced in Examples 1 to 3 and ComparativeExample 1 are evaluated for flatness, adhesiveness, film hardness andtransmittance in accordance with the following respective procedures. Acolor resist is applied to each of the transparent films, followed bypatterning. The number of pattern defects caused by various adversefactors, e.g., halation, is counted. The results are shown in Table 1.

{circle around (1)} Evaluation of Flatness

A height difference between central portions of red and green pixels(i.e. step height between the pixels) of a dummy color filter ismeasured. After each of the transparent films produced in Examples 1 to3 and Comparative Example 1 is applied to the dummy color filter, thestep height between the pixels of the color filter is measured. Theratio R of the step height (d1) before the application of thetransparent film to the step height (d2) after the application of thetransparent film is calculated by the equation (1) below:

R=d2/d1  (1)

The flattening performance of the thermosetting resin compositionsprepared in Examples 1 to 3 and Comparative Example 1 is classified intofive grades based on the following criteria: R>0.4 . . . Grade 1;0.4≦R≦0.3 . . . Grade 2; 0.3<R≦0.2 . . . Grade 3; 0.2<R≦0.1 . . . Grade4; R<0.1 . . . Grade 5. The higher is the grade, the better theflattening performance.

{circle around (2)} Tests for Adhesiveness and Chemical Resistance

After one hundred cross-cuts are scribed in the shape of cross stripeson each of the transparent films produced in Examples 1 to 3 andComparative Example 1, a peeling test (a cross-cut test) is conductedusing a cellophane tape. The peeling state of the cross-cuts is checkedby visual inspection to evaluate the adhesiveness of the transparentfilm. When no cross-cut is peeled, the adhesiveness is judged to be‘passed’. When one or more cross-cuts are peeled, the adhesiveness isjudged to be “failed.”

Further, the transparent film pieces are separately dipped inN-methyl-2-pyrrolidone (NMP) as an organic solvent, a 10% aqueous basicpotassium hydroxide solution and an acidic etchant solution (LCE-12K,CYANTEK CORPORATION) at 40° C. for 30 minutes, the procedure of theabove adhesiveness test is repeated to evaluate the chemical resistance.The peeling state of the cross-cuts is observed. When no cross-cut ispeeled after each dipping, the chemical resistance is judged to be“passed.” When one or more cross-cuts are peeled after each dipping, thechemical resistance is judged to be “failed.”

{circle around (3)} Evaluation of Film Hardness

After the transparent films produced in Examples 1 to 3 and ComparativeExample 1 are scratched using six kinds (1H-6H) of pencils (Statdler),damage to the films is observed. The strength of the films is classifiedinto six grades (1H-6H) according to the degree of the damage.

{circle around (4)} Evaluation of Pattern Defects (By halation)

A color resist for a CMOS image sensor is applied to each of thetransparent films formed in Examples 1 to 3 and Comparative Example 1,irradiated with light, and developed to form a pattern. The shape of thepattern is observed. The number of defects protruding from theboundaries of the pattern is counted. The pattern defects are caused dueto reflection of UV light from the underlying substrate, as shown inFIG. 2. The shapes of the patterns formed using the transparent filmsproduced in Comparative Example 1 and Example 1 are shown in FIGS. 3 and4, respectively.

TABLE 1 Physical Properties Example 1 Example 2 Example 3 ComparativeExample 1 Flatness Passed Passed Passed Passed Adhesiveness (Cross cut)100/100 100/100 100/100 95/100 Film Hardness (Pensile Hardness) 4H 5H 4H2H Chemical Resistance Acid Passed Passed Passed Passed Base PassedPassed Passed Failed Organic solvent Passed Passed Passed FailedTransmittance 365 nm 86.2% 91.7% 90.5% 99.5% 400 nm 98.6% 99.5% 99.2%99.8% Pattern Defects  3/100  8/100  7/100 27/100

As can be seen from the results of Table 1, the transparent filmsproduced using the thermosetting resin compositions prepared in Examples1 to 3 showed excellent characteristics in terms of flatness,adhesiveness, transmittance in the visible region and film hardness. Forexample, the films are substantially transparent to the passage ofradiation in the visible region and can exhibit, for example, a minimumtransmittance of visible radiation having a wavelength of 400 nm of atleast about 98%. In addition, the transparent films absorbed UV light of365 nm, contributing to a marked decrease in the number of patterndefects. For example, the films of the invention can exhibit a maximumtransmittance of radiation having a wavelength of 365 nm of about 92%.

As apparent from the foregoing, the thermosetting resin composition ofthe present invention is easy to handle and exhibits better chemicalresistance than conventional two-part thermosetting resin compositionsfor producing color filters. In addition, a transparent film for a colorfilter produced using the thermosetting resin composition of the presentinvention exhibits excellent flatness, adhesiveness, transmittance, filmstrength and heat resistance. Furthermore, the thermosetting resincomposition of the present invention has an ability to absorb UV light.Therefore, when the thermosetting resin composition of the presentinvention is used to produce a color filter for an image sensor, thenumber of pattern defects caused by halation and standing waves ofre-reflected UV light can be decreased.

Many modifications and other embodiments of the invention will come tomind to one skilled in the art to which this invention pertains havingthe benefit of the teachings presented in the foregoing descriptions.Therefore, it is to be understood that the invention is not to belimited to the specific embodiments disclosed and that modifications andother embodiments are intended to be included within the scope of theappended claims. Although specific terms are employed herein, they areused in a generic and descriptive sense only and not for purposes oflimitation, the scope of the invention being defined in the claims.

1. A thermosetting resin composition useful in the production of a colorfilter, the composition comprising an organic solvent and a self-curingcopolymer comprising structural units represented by Formulae 1, 2, 3,4, and 6:

wherein R₁ is a hydrogen atom or a methyl group and n is an integer from1 to 10;

wherein R₂ is a hydrogen atom or a methyl group and m is an integer from1 to 10;

wherein R₃ is a hydrogen atom or a methyl group;

wherein R₄ is a hydrogen atom or a methyl group and Z is selected fromthe following groups:

wherein X is selected from

o is an integer from 1 to 4, p is an integer from 4 to 12, and Y isselected from a hydrogen atom, C₁-C₄ lower alkyl groups and C₁-C₄ loweralkoxy groups.
 2. The thermosetting resin composition according to claim1, wherein the self-curing copolymer comprises about 5 to about 90 mol %of the structural unit of Formula 1, about 1 to about 30 mol % of thestructural unit of Formula 2, about 1 to about 30 mol % of thestructural unit of Formula 3, and about 0.5 to about 20 mol % of thestructural unit of Formula
 4. 3. The thermosetting resin compositionaccording to claim 1, wherein the self-curing copolymer comprises thestructural unit of Formula 6 in an amount of about 0.5 to about 20 mol%.
 4. The thermosetting resin composition according to claim 1, whereinthe self-curing copolymer has a weight-average molecular weight rangingfrom about 1,000 to about 1,000,000.
 5. The thermosetting resincomposition according to claim 1, further comprising an epoxy compound.6. The thermosetting resin composition according to claim 5, wherein thethermosetting resin composition comprises about 1 to about 45% by weightof the self-curing copolymer, about 1 to about 45% by weight of theepoxy compound, and the balance of the organic solvent.
 7. Thethermosetting resin composition according to claim 5, wherein the epoxycompound is selected from the group consisting of bisphenol A type epoxycompounds, bisphenol F type epoxy compounds, phenol novolak type epoxycompounds, cresol novolak type epoxy compounds, substituted epoxycompounds and mixtures thereof.
 8. The thermosetting resin compositionaccording to claim 1, wherein the self-curing copolymer furthercomprises at least one structural unit selected from the groupconsisting of: (meth)acrylates; acrylamides; styrenes;N-vinylpyrrolidone; N-vinylformamide; N-vinylamide; andN-vinylimidazole.
 9. The thermosetting resin composition according toclaim 8, wherein said (meth)acrylate is selected from the groupconsisting of methyl (meth)acrylate, ethyl(meth)acrylate,propyl(meth)acrylate, isopropyl(meth)acrylate, butyl(meth)acrylate, andbenzyl(meth)acrylate; said acrylamide is selected from the groupconsisting of N-methylacrylamide, N-ethylacrylamide,N-isopropylacrylamide, N-methylolacrylamide, N-methylmethacrylamide,N-ethylmethacrylamide, N-isopropylmethacrylamide,N-methylolmethacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide,N,N-dimethylmethacrylamide, and N,N-diethylmethacrylamide; and saidstyrene is selected from the group consisting of styrene,α-methylstyrene, and hydroxystyrene.
 10. The thermosetting resincomposition according to claim 1, further comprising at least onepolymer selected from poly(meth)acrylate, nylon, polyester, polyimide,polysilicon, and mixtures thereof.
 11. The thermosetting resincomposition according to claim 1, wherein said self-curing copolymercomprises a copolymer selected from the group consisting of

and mixtures thereof.
 12. A substantially transparent film derived froma self-curing copolymer comprising structural units represented byFormulae 1, 2, 3, 4, and 6:

wherein R₁ is a hydrogen atom or a methyl group and n is an integer from1 to 10;

wherein R₂ is a hydrogen atom or a methyl group and m is an integer from1 to 10;

wherein R₃ is a hydrogen atom or a methyl group;

wherein R₄ is a hydrogen atom or a methyl group and Z is selected fromthe following groups:

wherein X is selected from

o is an integer from 1 to 4, p is an integer from 4 to 12, and Y isselected from a hydrogen atom, C₁-C₄ lower alkyl groups and C₁-C₄ loweralkoxy groups.
 13. The film according to claim 12, wherein said filmexhibits a maximum transmittance of radiation having a wavelength of 365nm of about 92%.
 14. The film according to claim 12, wherein said filmexhibits a minimum transmittance of visible radiation having awavelength of 400 nm of at least about 98%.
 15. The film according toclaim 12, wherein said film exhibits a pensil hardness of at least 4H,as determined by scratching the film using six kinds (1H-6H) of pencils(Statdler).
 16. A color filter comprising a substantially transparentfilm derived from a self-curing copolymer comprising structural unitsrepresented by Formulae 1, 2, 3, 4, and 6:

wherein R₁ is a hydrogen atom or a methyl group and n is an integer from1 to 10;

wherein R₂ is a hydrogen atom or a methyl group and m is an integer from1 to 10;

wherein R₃ is a hydrogen atom or a methyl group;

wherein R₄ is a hydrogen atom or a methyl group and Z is selected fromthe following groups:

wherein X is selected from

o is an integer from 1 to 4, p is an integer from 4 to 12, and Y isselected from a hydrogen atom, C₁-C₄ lower alkyl groups and C₁-C₄ loweralkoxy groups.
 17. A color filter comprising a substantially transparentfilm formed using a thermosetting resin composition comprising anorganic solvent and a self-curing copolymer comprising structural unitsrepresented by Formulae 1, 2, 3, 4, and 6:

wherein R₁ is a hydrogen atom or a methyl group and n is an integer from1 to 10;

wherein R₂ is a hydrogen atom or a methyl group and m is an integer from1 to 10;

wherein R₃ is a hydrogen atom or a methyl group;

wherein R₄ is a hydrogen atom or a methyl group and Z is selected fromthe following groups:

wherein X is selected from

o is an integer from 1 to 4, p is an integer from 4 to 12, and Y isselected from a hydrogen atom, C₁-C₄ lower alkyl groups and C₁-C₄ loweralkoxy groups.
 18. An image sensor comprising a color filter comprisinga substantially transparent film derived from a self-curing copolymercomprising structural units represented by Formulae 1, 2, 3, 4, and 6:

wherein R₁ is a hydrogen atom or a methyl group and n is an integer from1 to 10;

wherein R₂ is a hydrogen atom or a methyl group and m is an integer from1 to 10;

wherein R₃ is a hydrogen atom or a methyl group;

wherein R₄ is a hydrogen atom or a methyl group and Z is selected fromthe following groups:

wherein X is selected from

o is an integer from 1 to 4, p is an integer from 4 to 12, and Y isselected from a hydrogen atom, C₁-C₄ lower alkyl groups and C₁-C₄ loweralkoxy groups.
 19. An image sensor comprising a color filter comprisinga substantially transparent film formed using a thermosetting resincomposition comprising an organic solvent and a self-curing copolymercomprising structural units represented by Formulae 1, 2, 3, 4, and 6:

wherein R₁ is a hydrogen atom or a methyl group and n is an integer from1 to 10;

wherein R₂ is a hydrogen atom or a methyl group and m is an integer from1 to 10;

wherein R₃ is a hydrogen atom or a methyl group;

wherein R₄ is a hydrogen atom or a methyl group and Z is selected fromthe following groups:

wherein X is selected from

o is an integer from 1 to 4, p is an integer from 4 to 12, and Y isselected from a hydrogen atom, C₁-C₄ lower alkyl groups and C₁-C₄ loweralkoxy groups.